| 摘要 |
PURPOSE:To discriminate the top or rear surface of recording paper correctly even with a change in humidity by providing a discriminating means which discriminates the top or rear surface of recording paper on the basis of a light quantity received by a light receiving element and a reference receiving light quantity determined by a humidity detected by a humidity detection means. CONSTITUTION:A humidity sensor 47 detects a humidity in an image forming device. In accordance with the detected humidity, a reference receiving light quantity is set to a reference receiving light quantity memory 55 in a RAM 54 on the basis of a reference receiving light quantity conversion table 53 in a ROM 51. When color developing paper 28 passes through a position below a top or rear surface detection sensor 40, a light emitting device 41. emits a parallel light to the surface of the color developing paper 28. The light reflected by the color developing paper 28 is received by a light receiving element 42. The light quantity received by the light receiving element 42 is inputted to a first A/D converter 48 and inputted to a CPU 50 as a digital value. The CPU 50 compares the input value from the first A/D converter 48 with the reference receiving light quantity set in the reference receiving light quantity memory 55 and discriminates the top or rear surface of the color developing paper 28 abutting on microcapsule paper 12. |
